Printing pressure control apparatus for intaglio press

ABSTRACT

Apparatus for applying and relieving the printing pressure between the plate cylinder and the impression cylinder of an intaglio press, including fast acting hydraulic motor driven means for moving one cylinder to and relieving the printing pressure. Wedge means are provided for adjusting the spacing between the plate cylinder axis and the impression cylinder axis. Motors drive the wedge means, and the control means for the wedge driving motors is interlocked with the control for the pressure applying and relieving apparatus so that the wedges cannot move while the cylinders are under printing pressure. The plate cylinder and the impression cylinder are connected by a square gear train of helical gears. One of the gears in the train is axially adjusted by a cam mechanism in response to the pressure applying and relieving movement of the one cylinder so that synchronous rotation of the plate cylinder and the impression cylinder is achieved at all relative positions of those two cylinders, and the pressure applying and relieving movements of the one cylinder are not accompanied by angular acceleration of either of the cylinders. Interlocking safety and sequence controls are provided between the pressure applying and relieving motors, the wedge adjusting motors, a sheet feeder control, a missing sheet detector, and a load cell mechanism which measures the pressure applied between the cylinders.

United States Patent 1191 Gazzola, deceased et al.

14 1 July 15, 1975 1 PRINTING PRESSURE CONTROL APPARATUS FOR INTAGLIO PRESS Primary E raminerEdgar S. Burr Assistant Examiner-Paul J. Hirsch [751 Inventors. Ivaldo Gazzola, deceased, late of Atmmm Agem Ur Fl.rm cooper Dunham Clark,

Lausanne, Switzerland; by Eles Griffin & Moran Gazzola; by Langranco Gazzola, heirs, both of Lausanne, Switzerland; Salvatore F. D'Amato, 1571 ABSTRACT Floral Park; Chauncey P. Foote, Jr., Apparatus for applying and relieving the printing pres- Katonah, both of NY, sure between the plate cylinder and the impression cylinder of an intaglio press, including fast acting hy- [73] Asslgnee g qf t Note Company draulic motor driven means for moving one cylinder 6W or to and relieving the printing pressure. Wedge means [22] Filed: Oct. 17,1972 are provided for adjusting the spacing between the plate cylinder axis and the impression cylinder axis. App! 298443 Motors drive the wedge means, and the control means for the wedge driving motors is interlocked with the [52] US Cl. 101/153; 101/152; 101/185; Control for the pressure applying and relieving appara- 10l/247 tus so that the wedges cannot move while the cylin- [51] Int. Cl. B411 9/02; 1341f 13/36 ders are under printing pressure. [581 Field of Search 101/284 2471 The plate cylinder and the impression cylinder are 101/185 1521 1531 2161 184; 72/237 244; connected by a square gear train of helical gears One 100/168 1691 170; 68/256 of the gears in the train is axially adjusted by a cam mechanism in response to the pressure applying and 1 1 References Cited relieving movement of the one cylinder so that UNITED STATES PATENTS synchronous rotation of the plate cylinder and the 5g5 72 5 92 m H 0 3 0 impression cylinder is achieved at all relative positions 1,779,310 10/1930 Fischerm, 101/184 X of those two cylinders, and the pressure applying and 2,207,785 7/1940 Crafts i 1. 101/153 relieving movements of the one cylinder are not 2,796,856 6/1957 Gratzmuller i i i 267/168 accompanied by angular acceleration of either of the 2,901,970 9/1959 Knops et a1, 1 1. 101/247 Cylinders 2,950,674 8/1960 Taylor et a1. 101/185 3.271122 9H9, Behringer 4 g 101/426 Interlocking safety and sequence controls are 3,315,203 4 1967 Ja ob 3 5 provided between the pressure applying and relieving 3,344,643 10/1967 Howard etaln. 72/244 motors, the wedge adjusting motors, a sheet feeder 3,369,383 2/1968 Barnikel i i i i i 72/244 control, a missing sheet detector, and a load cell 3 11/1969 Richard$-- 101/134 X mechanism which measures the pressure applied 3,601,046 8/1971 Motter i i 101/247 between h cylinders 3,670,644 6/1972 Hoever 1 1 i .1 100/47 3,732,813 5/1972 Singh et a1 101/247 x 14 Claims, 2 r wing Fig res 64s as a2 a 94 11 1 ?7Q PF SHEET SHEET N&

md ikl "-ATEZW'FHJUL a 5 m5 SHEET CONTACT CLOSED WHEN PRESS RUNNING PRINTING PRESSURE CONTROL APPARATUS FOR INTAGLIO PRESS CROSS-REFERENCE US. Pat. application Ser. No. 173,555, filed Aug. 20, 1971, now US. Pat. No. 3,762,319, issued Oct. 2, 1973, by the same inventors, entitled PLATE WIP- lNG MECHANISM FOR INTAGLIO PRESS discloses an apparatus which may be used on the same press with the present invention.

BRIEF SUMMARY OF THE INVENTION intaglio printing involves making impressions from the surface of a smooth plate, usually metal, having recesses, usually in the form of fine lines, in its surface. The recesses define the impression to be made. In making an impression from such a plate, ink is first applied to the plate, covering the recesses and at least adjacent parts of the smooth surface. The ink is then wiped from the smooth surface, leaving the ink only in the recesses in the plate. A sheet of paper or other material to be printed is then brought into contact with the plate under high pressure, forcing the paper into the recesses, so that the ink therein is transferred to the paper and reproduces on the paper an impression of the recesses in the plate surface. Typically, the plate is mounted on a cylinder, called the plate cylinder, and the paper is fed between the plate cylinder and an impression cylinder which is in rolling contact with the plate cylinder, thereby forcing the paper against the plate cylinder with substantial pressure.

The present invention relates to an improved mechanism for applying and relieving the printing pressure between the plate cylinder and the impression cylinder and for maintaining that pressure during the printing phase of the press cycle.

The plate cylinder and the impression cylinder are mounted on parallel shafts whose projecting ends are received in bearing blocks movable in vertical slideways located in the opposite side frame members of the press. On each side frame member is mounted a pressure applying and relieving mechanism including a hydraulic motor having a splined connection to a nut rotating in a fixed upper part of the frame. A threaded screw cooperates with the nut and is connected at its lower end to the bearing block which supports the upper one of the two cylinders. Actuation of the hydraulic motor moves the upper bearing block rapidly through a distance sufficient to apply or relieve the printing pressure between the cylinders.

The spacing between the axes of the two cylinders, when under pressure, is determined by a pair of wedge mechanisms, one located between the upper and lower bearing blocks on each side of the press. Each wedge mechanism comprises cooperating upper and lower wedge members, the lower wedge member being movable horizontally by a stepping motor driving a lead screw which is in threaded engagement with the lower wedge member.

The shafts carrying the plate cylinder and the impression cylinder also carry helical gears. In order to maintain the gears in synchronous rotation during a period when the printing pressure is relieved, the two cylinder shaft gears are connected through a square train of helical gears. One of the gears in the square gear train consists of two gears rotating on the same axis and connected by spline. A cam mechanism responds to the vertical position of the shaft which is shifted to apply and relieve printing pressure. This cam mechanism shifts one of the splined gears axially relative to the other to introduce into the square gear train an angular adjustment which compensates for the angular shift that would otherwise be caused by the pressure applying and relieving movement. Thus the pressure relieving and applying movement may be accomplished without angularly accelerating or decelerating either of the two cylinders.

As is conventional in intaglio presses, the plate cylin der has a first portion of its peripheral surface which is adapted to support a printing plate, and a second portion of smaller radius than the first portion, which provides space for means for gripping the ends of the plate, which is of flexible metal. Interlocking means is provided so that the printing pressure is applied, and in normal operation is relieved, only when the second portion of the plate cylinder is adjacent the impression cylinder. A load cell in the pressure applying mechanism can actuate the pressure relieving mechanism at any angular position of the plate cylinder, and thus operates as an emergency pressure relief.

Other interlocks ensure that the wedges are adjusted only after the pressure is relieved between the cylinders. A sheet feeding mechanism is interlocked with the wedge adjustment mechanism and the pressure relieving mechanism to ensure that, in normal operation, the supply of sheets to the press is stopped before the pressure is relieved.

DRAWINGS FIG. I is a fragmentary elevational view of an intaglio printing press embodying the invention, with certain parts broken away.

FIG. 2 is a sectional view taken on the line 2-2 of FIG. I on an enlarged scale.

FIG. 3 is a fragmentary sectional view taken on the line 33 of FIG. 2, on a further enlarged scale.

FIG. 3A is a sectional view, taken on the line 3A-3A of FIG. 3.

FIG. 4 is an enlarged sectional view, taken on the line 4-4 of FIG. 2, showing the wedge mechanism for adjusting the spacing between the axes of the plate and impression cylinders.

FIG. 4A is a fragmentary view on the line 4A-4A of FIG. 4.

FIG. 4B is an enlarged fragmentary view corresponding to a portion of FIG. 4A.

FIG. 5 is a sectional view taken on the line 5-5 of FIG. 4.

FIG. 6 is an elevational view taken from the left in FIG. 4.

FIG. 7 is a somewhat diagrammatic view showing the gearing connecting the plate and impression cylinders, taken on the line 7-7 of FIG. 2.

FIG. 8 is a view similar to FIG. 7, but on a larger scale, and with certain parts removed, taken on the line 88 of FIG. 9.

FIG. 9 is a sectional view taken on the line 99 of FIG. 7, on an enlarged scale.

FIG. 10 is a view similar to FIG. 9, showing a modified form of gearing.

FIG. I1 is a view partly in section and partly broken away, taken on the line llll of FIG. 10.

FIG. 12 is a developed view of the cams and gears in FIG. 10, taken along the line 12-12 of that figure.

FIG. 13 is a fragmentary developed view of the cams and gears of FIGS. 7-9 taken along the line 13l3 of FIG. 9.

FIG. 14 is a diagrammatic view illustrating the sheet feeding mechanism, the sheet detector, the printing pressure responsive control and a mechanism responsive to the angular position of the plate cylinder, all taken in a first angular position of that cylinder, and with the printing pressure relieved.

FIG. 15 is a view similar to FIG. 14, but with the cylinders in different angular positions and with the printing pressure applied.

FIG. 16 is a view similar to FIG. 14 but with the printing pressure applied.

FIG. 17 is a view similar to FIG. 15, with the printing pressure relieved.

FIG. 18 is a cross-sectional view taken along the line 18l8 of FIG. 14, showing the controls of FIG. 14 in mechanical detail.

FIG. 19 is a fragmentary view of the apparatus of FIG. 18, partly in right hand elevation, and partly in section, on the line 19- 19 of FIG. 18.

FIG. 20 is a wiring and hydraulics diagram illustrating the interlocking mechanisms.

DETAILED DESCRIPTION FIG. 1

The press illustrated includes a front vertical frame member 1 and a rear vertical frame member 2. Between the frame members 1 and 2 are journaled a plate carrying cylinder 3 and an impression cylinder 4. Sheets of paper to be printed may be supplied by conventional sheet feeding mechanisms to a train of sheet feeding rolls 5, 6, 7, from which they are transferred to the impression cylinder 4 and pass through the nip be tween the impression cylinder and the plate carrying cylinder 3. The printed sheets are then removed by a conveyor 9, running over a sprocket 8.

The press illustrated is a multicolor press. The ink applying mechanism includes a carriage 10 (FIG. 1) on which are mounted three ink reservoirs 11, 12 and 13 connected by ink conveying roller trains 15, 16 and 17 to rollers 20, 21 and 22, which transfer the ink to the plate on the cylinder 3. The rollers 20, 21 and 22 are contoured, so that each contacts a portion only of the surface of the cylinder 3. Typically, only one color of ink will be applied to any given portion of the surface of the plate, although it may be arranged that colors overlap, if desired.

The plate carrying cylinder 3 turns clockwise, as viewed in FIG. 1. A wiping roll 25 is rotatably mounted so that it runs with its periphery in contact with the plate cylinder 3, and also becomes immersed in a suitable cleaning liquid in a tank 26. The wiping roll 25 removes the ink from the surface of the plate, so that as the plate approaches the nip of the cylinders 3 and 4, the only ink remaining on the plate is in the recessed lines.

The plate cylinder 3 is driven by a motor 27 through a multiple V-belt drive 28 and a suitable gear train (not shown). Conveyor 9 is driven from the plate cylinder 5 through a bevel pass shown at 29 in FIGS. 1 and 2. The wiping roll 25 is driven by a motor 30, which may be controlled as described in our copending application Ser. No. 173,555, mentioned above.

The plate cylinder 3 is of a conventional type, well known in the art, having a first portion 3b of its peripheral surface (best seen in FIGS. 14-17) of constant radius and adapted to support a printing plate, and a second portion 3a of smaller radius than the first portion. The second portion serves as a recess to receive clamping means (not shown) for gripping and retaining the ends of a printing plate supported on the constant radius first portion.

FIGS. 2, 3 and 3A The apparatus for applying and relieving printing pressure between the plate cylinder 3 and the impression cylinder 4 is shown in greater detail in FIGS. 2 and 3. It includes a hydraulic motor 31 driving a nut 32 journaled in a cap 33 which is attached to the side frame 1, and closes the top of a slideway 1a formed in the side of the frame member 1. The plate cylinder 3 is supported on a shaft 34, whose ends are journaled in a pair of bearing blocks 35, vertically received in the slideway 1a and a corresponding slideway in the frame member 2 at the back of the press. Blocks 35 are fastened to the respective frame members 1 and 2. The impression cylinder 4 is mounted on a shaft 36 whose ends are journaled in a similar pair of bearing blocks 37. Between each pair of lower and upper bearing blocks 35 and 37, there is provided a wedge mechanism 38, including wedge members and 71 and shown in detail in FIGS. 4, 4A, 4B and 5, which controls the spacing between the axes of the shafts 34 and 36, when the cylinders are under pressure.

A connection is provided between nut 32 and the upper bearing block 37, so that the upper bearing block and the impression cylinder supported thereon may be raised and lowered a short distance by the action of the hydraulic motor 31.

The hydraulic motor 31 is any type of cylindrical hydraulic motor, an example of which may be seen in cross-section in FIG. 3A, and comprises a vane 40 fixed on a rotatable shaft 41, which extends along the vertical axis of the motor cylinder. The vane 40 is movable through somewhat less than one complete revolution, being limited in each direction so that it stops short of engagement with a fixed wall 410. Suitable hydraulic connections 42 and 43 are provided, through which operating fluid is supplied to the motor 31 so as to produce rotation of the shaft 41 from one end of its travel to the other, either in the direction to apply printing pressure between cylinders 4 and 3, or in the opposite direction, to relieve that pressure. The lower end of the shaft 41 is provided with splines 42.

A housing 44 is mounted on the top of the cap 33 by means of bolts 45. The motor 31 is fastened, by means not shown, on the top of the housing 44, and its shaft 41 projects downwardly through a suitable aperture in that housing.

The nut 32 is rotatably received within the cap 33 and is provided with an integral flange 32a at its lower end. An antifriction bearing 48 is located between the flange 32a and the under surface of the cap 33.

The upper end of the nut 32a projects above the cap 33 and is provided with an inwardly directed flange 32b having internal splines cooperating with the splines on the shaft 41. The periphery of the nut 32 is threaded at its upper end. A pair of lock rings 46 engage that threaded periphery and serve as an upper flange for the nut. Another antifriction bearing 47 is located between the lower ring 46 and the top of the cap 33.

The nut 32 is internally threaded and receives an externally threaded shaft 50. The lower end of the shaft 50 extends below the nut 32 and is integrally connected to an enlarged diameter portion which terminates in a downwardly depending skirt 51. The skirt 51 defines a recess which encloses a load cell 52, which may be of the electrical resistance strain gage type described in the patent to Jacobson, US. Pat. No. 3,315,203. The load cell 52 is provided with a connector 53 through which suitable external electrical connections may be made. The upper end of the load cell abuts against the inner end of the recess defined by the skirt 51. The lower end of the load cell rests on a connecting plate 54, which is attached to the top of the bearing block 37 by means of bolts 55. The lower end of the skirt 51 is connected to the plate 54 by means of a lost motion connection, which limits the upward movement of the skirt 51 with respect to plate 54, but allows substantial downward movement, to accommodate compression of the load cell required by its force measuring function. The lost motion connection comprises a plurality of screws, one of which is shown at 56, threadedly engaging recesses in the skirt and having heads received in recesses in the under side of the plate 54. The screws 56 do not threadedly engage the plate 54, but are free to move downwardly a short distance, as determined by the spacing between the lower end of their heads and the bearing block 37. The screws 56 are also effective to hold the shaft 50 against rotation, so that rotation of nut 32 is effective to move the shaft 50 vertically.

A lower oil retaining housing 57 is attached to the under side of the cap 33 and encloses the lower end of nut 32. The housing 57 is provided with a central aperture which receives the periphery of the skirt 51. A seal ring 58 is provided between housing 57 and the skirt 51. The space between the housings 57 and 44 is filled with oil or other suitable lubricant, since the threads of the nut 32 and shaft 50 are under considerable stress during the operation of the press. The shaft 50 is provided with a central bore 50a, which communicates at its lower end with the housing 57. The upper end of the nut 32 is provided with a bored passage 32c, which provides fluid communication between the interior of the housing 44 and the space between the splined end of shaft 41 and the upper end of shaft 50. The passages 32c and 50a cooperate to relieve hydraulic pressure in the oil within the housings 44 and 57 during rotation of the nut 32 by motor 31.

A plurality of compression spring means 60 are retained between the plate 54 and the cap 33. Each spring means 60 comprises an external cylinder 61, a piston 62 received in the upper end of the cylinder 61, and a spring 63 encircling the lower end of a downward extension of the piston 62. The upper end of piston 62 is received in a recess in the cap 33. The lower end of cylinder 61 is provided with an extension of smaller diameter received within a recess in the plate 54.

The function of the several spring means 60 is to limit the upward travel of the bearing block 37, when it is driven by the motor 31. In this way, the vane 40 of the motor 31 has a range of travel which is somewhat less than one complete revolution. Since the block 37, the shaft 36 and the plate cylinder 3 supported thereby are quite massive, it is desirable to have the impact at the end of the upward travel of those parts taken by some structure other than the vane 40. In the apparatus illustrated, this impact is taken by the shoulders at the ends of the cylinders 61. The upper end of each cylinder 61 abuts against the cap 33 at the top of the stroke of the motor 31. The shoulders at the bottom ends of the cylinders 61 are in continuous engagement with the upper surface of the plate 54. Thus, when the motor 31 raises the bearing block 37 and related parts upwardly to relieve the printing pressure, the impact at the end of the upward stroke is taken by the cylinders 61. The springs 63 absorb energy throughout the upward travel of the blocks 37 and thus diminish to some extent the energy of the impact.

The cap 33 is held on the frame member 1 by means of two bolts 64 whose heads are received in recesses in frame 1, and whose upper ends extend upwardly through the cap 33, where they are engaged by nuts 65.

A cover 66 encloses the nuts 65 and the housing 44.

FIGS. 4-6

These figures illustrate the wedge mechanism 38 for adjusting the spacing between the axes of the plate cylinder 3 and the impression cylinder 4. The wedge mechanism includes a lower wedge member 70 having a horizontal under surface and an inclined planar upper surface, and a cooperating upper wedge member 71 having an inclined planar under surface and a horizontal upper surface. The two wedge members 70 and 71 are enclosed within a cage consisting of a base plate 72, end plates 73 and 74 and side plates 75. The cage 72, 73, 74, 75 is utilized to hold the wedge members 70 and 71 together as an assembly with other parts of the wedge mechanism 38. The handling of the wedge mechanisms as assemblies facilitates their installation in the slideways in the frame members 1 and 2. A pair of screws 76 (FIGS. 4A and 4B) are threaded into and extend through the front side plate 75. The screws 76 have on their inner ends eccentric pins 76a, which project into the path of the lower wedge member 70, so as to limit its travel. By rotating the screws 76, the positions of the pins 76a may be adjusted. A locking collar 76b (FIG. 4B) encircles the outer end of each of the screws 76. By tightening the collar 76b, the pin 76a may be fixed in any adjusted position. The range of movement of wedge member 70 is limited to a distance, relatively short as compared to the length of the wedge, and centered on the slideway 1a.

The lower wedge member 70 is substantially shorter than the upper wedge member 71 and has an internally threaded aperture for receiving a lead screw 77. A spring 79 is held in compression between the wedge member 70 and end plate 74, and serves to take up lost motion between the lead screw 77 and the wedge member 70. The lead screw is journaled in a bearing 78 fastened to the end plate 73. The end of the lead screw outside the bearing 78 is connected through a universal joint 80 to a drive shaft 81 extending through an aperture in the frame member 1. The lefthand end of the drive shaft 81, as it appears in the drawing, is supported by bearing 82 mounted in a plate 83, fastened to frame member 1. A pair of clutch members 84 and 85 are fixed on the shaft 81 and have opposed spaced toothed clutch faces. Between the clutch members 84 and 85, there is rotatably mounted on the shaft 81 a third clutch member 86 having a gear 86a formed on its periphery.

Clutch member 86 has on its ends faces respectively adapted to engage the clutch members 84 and 85. All the clutch faces of the members 84, 85, 86 are provided with one-way teeth, so that the clutch faces transmit motion in only one direction of rotation. The clutch faces on members 84 and 85 are arranged to transmit motion in opposite directions.

The clutch member 86 is provided with a groove 86b in which the arms of a fork 87 are received. The lower end of the fork 87 is connected to armature 90 of an electromagnet 91, which acts as a clutch drive motor. The armature 90 is spring biased to a position in which the right-hand clucth face of the clutch member 86 is engaging the clutch member 84. The electromagnet 91 may be energized for operation of the armature 90 away from the position shown, so as to operate the clutch member 86 to engage clutch member 85.

A gear 86a on the periphery of clutch member 86 cooperages with a rack 92 operated by a wedge stepping linear motor 93. The rack 92 is biased to one end of its stroke by means of a spring 94, as shown in FIG. 5, and may be driven to the opposite end of its stroke by energization of a coil 95.

The electromagnet 91 serves as a clutch drive motor and the electromagnet 93 serves as a linear, single stroke, spring return motor for producing a stepping movement of the wedge member 70.

The left end of the shaft 81, as viewed in FIG. 4, drives through conventional gearing shown diagrammatically at 79, a pair of concentric shafts which extend through a cover plate 96 mounted on the frame member 1. Outside of the cover plate, the concentric shafts respectively carry an indicator dial 97 and a revolution counting pointer 97a, both of which cooperate with a stationary scale 98, to show the position of the wedge 70, and hence the spacing between the axes of cylinders 3 and 4. A suitable casing with a window 99 encloses the indicator dial 97, pointer 97a and scale 98. The casing 100 also serves as a support for an array of manual controls 151, 152, and 160, and indicator lamps 161 and 162, described more completely below in connection with FIG. 16. The casing 100 with its indicator and controls are on the right side of the press as viewed in FIG. 2. A similar indicator and control array is provided on the left side of the press. The lefthand side controls are shown at 151a, 152a and 160a in FIG. 20, and the left indicator lamps at 161a and 162a.

Instead of the power driven control arrangement shown, a hand wheel could be used to rotate an extension of shaft 81 to adjust the wedges.

The wedge member 71 is provided in its upper surface with recesses 71a, in which are received pistons 88, resting on conical springs 89. When the printing pressure is relieved, the springs 89 are effective to lift the pistons 88 slightly, thereby making the downward force on the wedge member 71 a resilient load instead of a dead load, and facilitating the movements of the wedge member 70. Springs 89 also absorb some of the energy in the rapidly downwardly moving boxes 37 when printing pressure is applied. For example, at a press speed of 8000 sheets per hour, the impression cylinder 4 must be moved to its pressure applying position in about 0.09 seconds.

The clutch member 86 is always engaging either the clutch member 84 or clutch member 85. When the clutch member 86 is engaging the clutch member 84,

as shown in the drawings, and the clutch member 86 is reciprocated by the motor 93, then the clutch member 86 drives the clutch member 84 and shaft 81 in the counterclockwise direction, as viewed in FIG. 5, thereby driving the wedge member 70 to the right as shown in FIG. 4, and increasing the spacing between the axes of the shaft 34 and 36.

When the clutch member 86 is engaging the clutch member 85, and clutch member 86 is reciprocated by the motor 93, then the clutch member 85 and shaft 81 are driven in the clockwise direction, driving the wedge member 70 to the left, and decreasing the spacing between the axes of the shafts 34 and 36.

FIGS. 7-9 AND 13 These figures illustrate a gearing mechanism connecting the shafts 34 and 36 of the plate cylinder and the impression cylinder respectively. This gearing mechanism ensures synchronous rotation of the two shafts at all times, even when the shafts are being moved toward and away from each other by the pressure relieving mechanism, or by the spacing adjusting wedge mechanism. The shaft 34 of the plate cylinder 3 has fixed thereon a helical gear 101. The shaft 36 of the impression cylinder 4 has fixed thereon a helical gear 102. The two shafts 34 and 36 are always operated in synchronism by virtue of the gearing mechanism to be described.

Gear 101 meshes with a helical gear 103 fixed on a shaft 104, journaled in the frame of the press. Gear 102 meshes with a helical gear rotatable on a stub shaft 106, fixed in the frame 1 of the press. Another helical gear 107 meshes with the gear 103 and is rotatable on the shaft 106. Gear 105 has a splined connection 100 with the gear 107 so that both of those gears rotate in unison on the shaft 106. The gear 105 is shiftable axially on the shaft 106 by means of a cam mechanism including a cam 111 rotatable on the shaft 106 and a cam follower 112 cooperating with the cam 111 and attached to a plate 113 fixed against rotation by means of guide bolts 114, and slidable axially on the shaft 106. A second plate 115 is also slidable axially of shaft 106 on the guide bolts 114. The plate 115 spans the gear 105. Antifriction bearing means are provided at 116 and 117 between the plates 113 and 115, respectively, and the gear 105. The cam 111 has attached to its periphery an arm 120 (FIGS. 8-9) having a fork at its outer end to receive a pin 121 at one end of a bell crank lever 122, pivoted at 119. The other end of the bell crank lever 122 has a fork 1220 to receive a pin 123 fixed on a post 124 attached to the bearing block 37 which supports the shaft 36.

The helical gears 102 and 105 are always in mesh, and the gears 107 and 101 are always in mesh with gear 103. Since gears 105 and 107 rotate in unison, all the gears mentioned are rotating synchronously with respect to one another when the block 37 is stationary. When the bearing block 37 is moved upwardly or downwardly, as during relief or application of pressure between the plate cylinder 3 and the impression cylinder 4, then the motion of the block 37 introduces into the gear train an additional rotation, which, if uncorrected, would require acceleration or deceleration of either cylinder 3 or cylinder 4 in order to maintain synchronism between gears 101 and 102. Since these cylinders are large and massive, the necessary acceleration or deceleration would require either substantial force or substantial time, or both. The cam mechanism described above, including cam 111 and follower 112, responds to vertical movement of block 37 by introducing a corrective rotation into the gear train through axial movement of the helical gear 105. As block 37 moves, pin 123 rotates bell crank lever 122, so that pin 121 shifts the arm 120, thereby rotating cam 111 and shifting its follower 112 axially along shaft 106. This motion of follower 112 carries gear 105 along with it. Since the helical gears 105 and 102 remain in mesh, this axial motion of helical gear 105 is necessarily accompanied by rotation of that gear, which rotation exactly compensates for the additional rotational movement between gears 102 and 105 introduced by the linear movement of shaft 36, so that the cylinders 3 and 4 can remain in synchronism throughout any movement of the bearing block 37 within the limited range required for applying and relieving pressure between cylinders, or within the range required for adjusting the spacing between the shafts 34 and 36 by means of the wedge members 70 and 71. Springs 125 encircle the guide bolts 114, between the heads of those bolts and the plate 115. Springs 125 bias the plates 115 and 113 and the cam follower 112 into engagement with the cam 111, so that follower 112 is at all times positioned in accordance with the position of cam 111.

All the gearing is located outside the frame members 1 and 2, thereby reducing the spacing between the frames and the deflection of the cylinder shafts under load.

FIGS. 12

These figures illustrate a modified form of gearing which may be used in place of that shown in FIGS. 7-9, and which eliminates the use of the biasing springs 125. In these figures, two cams are used, namely the cam 111 and another oppositely facing cam 126 fixed to the cam 111 for concurrent movement therewith by a plurality of rods 127. The cam 111 cooperates with a follower 112, as in the previous modification. Followers 112 is held against rotation by a plurality of fixed pins 128, and is moved axially along the stub shaft 130, which corresponds in function to the stub shaft 106 of FIG. 9. Antifriction bearing 116 is located between plate 113 and gear 105. Gear 105 performs the same function as the correspondingly numbered gear in FIG. 9. The cam 126 cooperates with a follower 131 mounted on a plate 132, which is also held against rotation by the fixed pins 128. An antifriction bearing 133 is located between plate 132 and gear 105. A gear 134 which corresponds in function to the gear 107 of FIG. 9 is mounted at the lower end, as viewed in FIG. 10, of an elongated cylindrical sleeve 135 whose upper end is splined to the gear 105.

It may be seen that the gear 105 is trapped between the two followers 112 and 126 and is positively moved in either axial direction as required to compensate for rotation of the shaft 36 which might be introduced into the gearing by movement of the bearing block 37. Since the springs 125 are eliminated, any end thrust on the gears due to the presence of those springs is also eliminated. Any wear on the gears due to the presence of the continuous end thrust of the springs is thereby eliminated.

An antifriction bearing 136 is provided between the cam follower 126 and the sleeve 135. Antifriction bearings 137 and 138 are provided between the upper and lower ends of sleeve and the stub shaft 130.

FIGS. 14-19 FIGS. 14-17 illustrate, somewhat diagrammatically, certain control elements which are used on the press, and which are connected in the circuits of FIG. 20. FIGS. 18 and 19 illustrate the mechanical details of those control elements.

The final cylinder 7 of the sheet feeder train carries a set of grippers 140 which engage the leading edge of a sheet of paper and transfer it to another set of grippers 141 on the impression cylinder 4. Two of the grippers 141 on the impression cylinder 4 constitute a sheet detector means and for that purpose are provided with electrical connections so that when the grippers are closed and no sheet is located between them an electrical circuit is completed through the grippers. The structure of the grippers and their electrical operation may be the same as that disclosed in the patent to Babicz, US Pat. No. 2,432,133.

A printing pressure responsive switch 142 is mounted on the frame member 1 and is operated by an actuator 143 cooperating with a disc 1430 fixed on a hub 144 on the end of shaft 36 which carries the impression cylinder 4. The contacts of the switch 142 are closed when impression cylinder 4 is in printing contact with the plate cylinder 3, as shown in FIGS. 15 and 16. The contacts of switch 142 are open when the impression cylinder 40 is lifted so that there is no pressure between that cylinder and the plate cylinder 3, as shown in FIGS. 14 and 17. An armature 145 is fixed in a groove 1440 in an insulating plate 144b on the end of hub 144, and cooperates with a stationary coil 146 to generate a signal in that coil whenever the armature 145 is passing in close proximity to the coil, as shown in FIGS. 15 and 17. The coil 146 and armature 145 cooperate as a detector of the angular position of impression cylinder 4. The signals produced in coil 146 control circuits which permit application or relief of printing pressure only when the gaps 3a and 4a of the cylinders 3 and 4 are opposed, so that the stresses in the cylinders are relieved. The circuitry associated with the coil 146 is illustrated diagrammatically in FIG. 20.

FIG. 14 shows the parts in their positions when the cylinders are not under printing pressure and a sheet has just been transferred from the feeder roll 7 to the impression roll 4.

In FIG. 15, the cylinders have rotated through approximately 45 from the position shown in FIG. 13, so that the armature 145 is passing the coil 146, and pressure is being applied between the cylinders 3 and 4. The contacts of switch 142 are closed.

In FIG. 16, the cylinders are in the same relative angular positions as in FIG. 14, but the feeder roll 7 has not transferred a sheet to the impression cylinder 4, so that the circuit through grippers 141 is completed. However, pressure has been applied between the cylinders to print the previous sheet, so that the contacts of switch 142 remain closed.

In FIG. 17, the cylinders are in the same relative angular positions as in FIG. 15. As explained more fully below in connection with FIG. 20, the closing of the electrical circuit through the grippers 141, in the position of FIG. 16, causes the signal produced in the coil 146 as the armature 145 passes it to initiate an operation of the motors 31 to relieve the pressure between the plate cylinder 3 and the impression cylinder 4. The switch 142 is shown as having been opened by that pressure relieving operation.

FIG.

This figure illustrates the control apparatus, partly electrical and partly hydraulic, which is used in connection with the press. This apparatus comprises certain elements shown in FIG. 6, including the spacing adjustment selector 160, which is a key operated switch and determines whether the adjustment is to be made to increase or decrease the printing pressure; two indicator lamps 161 and 162, which show whether the selector 160 is set to increase the pressure or to decrease the pressure; and two spacing adjustment push button switches 151 and 152. The switch 151 causes adjustment of the pressure at both the right and left end of the cylinders, as viewed in FIG. 2. Actuation of push button switch 152 causes adjustment of the pressure at the right end of the cylinder only.

The control assembly in FIG. 6 is located at the righthand side of the press. A similar control assembly is located at the left-hand side of the press and is shown only in FIG. 20. The left-hand side control elements are give numerals the same as those of the right-hand side control elements, with the letter a added. Thus, selector 160a is the left-hand side control element corresponding to selector 160 on the right-hand side. The only difference is that the switch 152a causes adjustment of the pressure at the left-hand side of the cylinders only, whereas the switch 152 causes adjustment of the pressure at the right-hand side.

The use of dual controls at the opposite sides of the press allows the pressman to change the cylinder axis spacing from the most convenient point. The use of key operated switches for the selectors 160 and 160a prevents the setting of the two opposite side controls for conflicting pressure adjustment operation. Thus, it is intended that only one key be in possession of the pressman. If he has the key in the switch at the righthand side of the press, he cannot then set the pressure control on the left-hand side without first transferring the key. Trap key switches are used, so that when either switch is in an ON position, the key is trapped and it cannot be removed until the switch is turned OFF.

There are also shown in FIG. 20, certain manual controls which do not appear in any other figure of the drawings, namely a pressure applying push button switch 153; a pressure releasing push button switch 154', a feeder start push button switch 155 and a feeder stop push button switch 156; and a switch 166, which is closed when motor 27 is energized and open when that motor is de-energized.

Certain other controls appearing in FIG. 20 are not manually actuated, and include a switch 141, shown in this figure as a single contact switch, which corresponds in function to the sheet detecting grippers 141 of FIGS. 14-19; a printing pressure detector switch 142, shown as to its mechanical structure in FIGS. 18-19 and as to its function in FIGS. 14-17; an angular position detector 146, shown in FIGS. 14-19; and two load cells 52R and 52L, each corresponding to the load cell 52 appearing in FIG. 3. Load cell 52R is located at the right-hand side of the press, as viewed in FIG. 2. Load cell 52L is located at the left-hand side.

The devices actuated in response to the manual and automatic controls identified above including clutch actuating motors 91R and 91L, each corresponding to hydraulic motor 91 of FIG. 4; linear single stroke motors 93R and 93L, corresponding to the electric motor 93 appearing in FIG. 5; and a sheet feeder 96, shown only diagrammatically, which may be of conventional construction; and pressure applying and relieving motors 31R and 31L, corresponding to the motor 31 of FIGS. 1-3 and 3A.

The spacing adjustment selectors 160 and 1600 control relays 163 and 163a, which determine whether the motors 91R and 91L are to be actuated to a decreasing pressure position or an increasing pressure position.

The spacing adjustment push button switch 152 controls a circuit for a time delay relay 147, which in turn controls the wedge stepping motor 93L. The spacing adjustment switch 152a controls a circuit for a time delay relay 147a, which in turn controls the wedge stepping motor 93R. The switches 151 and 1510 control circuits for both relays 147 and 147a and hence control circuits for both the motors 93L and 93R. In order to adjust the wedges to change the spacing between the axes of the cylinders 3 and 4, it is necessary that the pressure between the cylinders 3 and 4 be relieved. In other words, switch 142 must be opened, relay 192 de-energized and its back contact 192a must be closed. Switch 142, relay 192 and contact 192a constitute an interlocking means to prevent movement of the wedge member unless the pressure between cylinders 3 and 5 is relieved. No accidental operation of the spacing selection mechanism is possible, since the switches 160 and 160a are trap key switches which hold their selected positions with the key trapped, so that it may be withdrawn only in the center of OFF position of the switch. There is only one key available, so that switches 160 and 160a cannot be set in conflicting positions.

In order for the pressman to make a spacing adjustment, it is necessary to actuate one of the two selector switches 160 and 160a in one direction or the other, and to actuate either of the two push button switches and 150a. If it is desired to change the spacing on one side only of the press, for example, assume that the selector switch is operated to close against its righthand stationary contact as shown in FIG. 20, to select an increasing spacing adjustment (lower printing pressure), indicating lamps 161 and 161a are thereby lighted and relay 163a is energized. Energization of relay 163a closes its contact 163a-2 and thereby energizes a solenoid 165a which actuates a control valve 165 to supply fluid to both clutch actuating motors 91L and 91R to operate them to their spacing increasing positions. Furthermore, closure of contact 1630-1 prepares a circuit for the four push button switches 151, 152, l5la and 152a.

Let it be further assumed that it is now desired to increase the spacing between the cylinders at the righthand end only. Push button switch 1520 is closed. It may be closed only momentarily, or it may be held down but the effect in either instance is the same. The time delay relay 1470 is energized and motor 93R is energized over contact 1470-3. Time delay contact 1470- l and instantaneous contact 1470-2 are connected in series and provide a holding circuit for maintaining the energization of relay 1470 for a predetermined time. long enough to permit the motor 93R to complete one stroke. If the switch 1520 is held down, only one stroke of the motor 93R is produced, since the relay 1470 is not then deenergized by time delay contact 7:14. but remains energized by a circuit through switch 152a, thereby maintaining the circuit for the motor 93R energized. Only by releasing the push button 152a is it possible to produce another single stroke cycle of the motor 93R.

If it is desired to adjust the spacing at both sides of the cylinders at the same time, then either switch 151 or 1510 is used. If it is desired to adjust the spacing on the left side only, then switch 152 is used.

Although positive and negative power supply lines are indicated by legends in the drawings, the circuit illustrated is obviously equally adaptable to the use of alternating current.

When starting up the press, the pressure between the cylinders 3 and 4 is normally relieved so that switch 142 is open. There is usually no sheet then passing through the press, so that switch 141 is closed. The wedges 38 will have been adjusted to produce the proper printing pressure when pressure is applied by actuation of the motors 31R and 31 L. After the press is started by energization of motor 27, so that contact 166 is closed, the feeder is started by closure of the push button switch 155. The first sheet which travels through the feeder rolls 5, 6 and 7 and reaches the position between the feeder roll 7 and impression cylinder 4 in FIG. 14, is there inserted between the jaws of the grippers 141, breaking the electrical circuit between those grippers and effectively opening the no sheet detector switch 141 in FIG. 20.

The pressman may now apply printing pressure between the cylinders by actuating the push button switch 153. Closure of that switch energizes a relay 206, which closes a holding contact 2060 to maintain energization of relay 206 after the push button switch 153 is released. Contact 206b closes, preparing a circuit for energizing solenoids 197 and 198. Contact 206c closes concluding a circuit through the angular position conductor coil 146.

When the armature 145 reaches the angular position of FIG. 15, a signal is generated in the coil 146 and is amplified by an amplifier 146a to actuate a relay 146b and close a contact 1460 momentarily. This completes the circuit for energizing solenoids 197 and 198, which are effective to shift the valves 200 and 201 so that hydraulic fluid is supplied to the motors 31L and 31R to actuate those motors to apply pressure between the cylinders 3 and 4.

When pressure is applied between the cylinders 3 and 4, the switch 142 is closed (see FIG. Consequently, the relay 192 is energized, and its contacts are reversed from the positions shown in the drawing. Contact 192a is now open, preventing the making of any manually controlled adjustment of the spacing between the axes of the two cylinders. Contact 1921; is opened, thereby preventing a new energization of relay 206. Contact 1920 is closed, preparing a circuit for energizing a relay 190.

The manually controlled operation for relieving the pressure is the same as that described above, except that relay 190 is energized by actuation of switch 154, instead of relay 206, resulting in the energization of solenoids 210 and 211, instead of solenoids 197 and 198. The solenoids 210 and 211 are effective to reverse the motors 31L and 31R, thereby lifting the impression cylinder 4 to its pressure releasing position.

Let it now be assumed that the cylinders 3 and 4 are in running contact and that it is desired to release the pressure between them by actuation of the push button 154. The switch 154 is momentarily closed, energizing relay 190, which closes a holding contact 190a to maintain the energization of that relay after the push button switch 154 is released. Contact 190b prepares a circuit for energizing solenoids 210 and 211. Contact lc completes the circuit through the coil 146. When the armature passes the coil 146, as in FIG. 17, the amplifier [460 receives a signal and energizes a relay 1461; to close a contact 146a momentarily. This completes a circuit for energizing the solenoids 210 and 211 which shifts the valves 200 and 201 to reverse the connections to the hydraulic motors 31R and 31 L so that the motors are actuated to relieve the pressure between the cylinders 3 and 4. When the pressure between those cylinders is relieved, switch 142 is opened, as shown in FIG. 17. Consequently, relay 192 is de-energized and its contacts are moved to the positions shown in the drawing, in which the circuits are again prepared for a new application of pressure.

When no sheet is present at the grippers 141, the circuit through those contacts, which appear as a single contact 141 in FIG. 20, is closed, energizing relay 190. The operation is then the same as though the push button switch 154 was actuated.

As mentioned above, energization of relay may be initiated either by actuating the push button 154 or by the no sheet detector switch 141. In either case, the coil 146 is effective to prevent energization of the solenoids 210 and 211 until the gaps in the cylinders 3 and 4 are opposite each other.

The two load cells 52R and 52L are arranged to energize, through suitable amplifiers, one winding or the other of a dual winding relay 158. The relay 158 is arranged to close its contact 158a whenever the load measured by the cells exceeds a predetermined value, which may be adjusted. When contact 158a is closed, the solenoids 197 and 198 are energized, regardless of the angular positions of the cylinders 3 and 4.

The reason for this mode of operation is that the load cells 52R and 52L are set to operate the relay 158 only when there is a substantial pressure overload between the cylinders, such as may be caused to a tool or other foreign object passing through the nip of the cylinders. Under such circumstances, it is desirable to prevent damage to the press by relieving the pressure immediately, even though it interrupts the printing operation.

The vertical position of the impression cylinder 4 may be changed only by rotating the nuts 32 on the threaded shafts 50. When the impression cylinder 4 is moved downwardly to its printing position by rotation of nuts 32, the cylinder is locked in that position, in the sense that it can only be moved upwardly by a reverse rotation of nuts 32. The development of high pressure between the cylinders 3 and 4 cannot by itself drive the nuts in the reverse direction, due to the low pitch of the threads. However, the cylinders 3 and 4 are protected against overloads by the load cells 52R and 52L, which are efi'ective to cause reverse rotation of the nuts 32 when an overload condition occurs.

We claim:

1. An intaglio printing press, comprising:

a. frame means including opposed side frame members having opposed vertically extending slideways open at the top;

b. a plate cylinder fixed on a shaft whose ends project inside said slideways adjacent the lower ends thereof;

c. lower bearing blocks slidably received in said slideways and rotatably receiving the ends of the shaft;

d. an impression cylinder fixed on a shaft whose ends project into the slideways above the ends of the plate cylinder shaft, said impression cylinder being adapted to run in rolling contact with the plate cylinder;

e. upper bearing blocks slidably supported in the slideways and rotatably supporting the ends of the impression cylinder shaft;

f. means for moving one of the cylinders with respect to the other cylinder to apply and relieve pressure at the line of contact between said plate and impression cylinders;

g. means connecting the plate cylinder and the impression cylinder for synchronous rotation including:

1. first helical gear means fixed on the shaft of the plate cylinder;

2. second helical gear means engaging said first helical gear means;

3. third helical gear means engaging said second helical gear means; and

4. fourth helical gear means fixed on the shaft of the impression cylinder and engaging said third helical gear means;

h. one of said second and third helical gear means comprising two gears rotatable about a common axis and splined together for concurrent rotation and relative axial movement, and means holding one of said two gears against axial movement;

i. cam means for moving the other of said two gears axially in response to vertical movement of said one cylinder to introduce a compensating rotation into the gear train, so that the impression cylinder and the plate cylinder do not change their relative angular positions during that vertical movement.

2. An intaglio printing press as in claim I, in which:

a. said cam means comprises a cam connected to the bearing block for said one cylinder for concurrent movement therewith;

b. a follower for the cam connected to said other gear for concurrent rotation therewith; and

c. spring means biasing said follower and said cam into engagement.

3. An intaglio printing press as in claim 1, in which:

a. said cam means comprises two spaced oppositely facing rotatable cams connected to the bearing block for said one cylinder for concurrent movement therewith; and

b. two followers, one cooperating with each of said cams, and both fixed to said other gear, so that said other gear is positively driven in each direction by said cam means.

4. An intaglio printing press as in claim 1, in which:

a. the plate cylinder has a first portion of its peripheral surface adapted to support a printing plate, and a second portion of smaller radius than the first portion;

b. motor means for driving said cylinder moving means;

c. manual control means for said motor means, and

d. interlocking means responsive to the angular position of the plate cylinder and efi'ective to prevent actuation of said motor means except when the line of contact between the plate cylinder and the pressure cylinder is located at said second portion of the plate cylinder surface.

5. An intaglio printing press, comprising:

a. frame means including opposed side frame members having opposed vertically extending slideways open at the top;

b. a plate cylinder fixed on a shaft whose ends project into said slideways adjacent the lower ends thereof;

c. lower bearing blocks slidably received in said slideways and rotatably receiving the ends of the shaft;

d. an impression cylinder fixed on a shaft whose ends project into the slideways above the ends of the plate cylinder shaft, said impression cylinder being adapted to run in rolling contact with the plate cylinder;

e. upper bearing blocks slidably supported in the slideways and rotatably supporting the ends of the impression cylinder shaft;

f. a pair of caps fixed on said side frame members and closing the upper ends of the slideways;

g. means on each cap for vertically moving the associated upper bearing block to apply and relieve pressure between said plate and impression cylinders, each said vertically moving means compris- 1. an internally threaded nut rotatably mounted in an aperture in the cap and having peripheral flanges at its upper and lower ends, respectively above and below the top and bottom surfaces of the cap;

2. antifriction bearing means between said flanges and the cap;

3. an externally threaded shaft, fixed against rotation, said shaft being received in said nut and extending downwardly below the lower end of the nut;

4. means for measuring the pressure between said plate and impression cylinders, including a load cell having an upper end supporting the lower end of the threaded shaft;

5. connecting means supporting the lower end of the load cell and fastened to the top of the bearing block;

6. said nut having an internally splined projection extending above the upper end of the shaft and aligned with the axis of the shaft; and

7. motor means mounted on the cap above the upper end of the nut for rotating the nut, said motor means having a downwardly extending shaft with external splines cooperating with the internal splines on the nut.

6. An intaglio printing press as in claim 5, including compression spring means retained between the plate and the cap, said compression spring means comprising:

a. a plurality of horizontally spaced cylinders having shoulders at their lower ends resting on the plate, and having projections on their lower ends received in recesses in the plate;

b. a plurality of pistons, one slidable within each of said cylinders; and

c. a spring compressed between each cylinder and its associated piston and biasing the piston upwardly into a recess in the cap; 

1. An intaglio printing press, comprising: a. frame means including opposed side frame members having opposed vertically extending slideways open at the top; b. a plate cylinder fixed on a shaft whose ends project inside said slideways adjacent the lower ends thereof; c. lower bearing blocks slidably received in said slideways and rotatably receiving the ends of the shaft; d. an impression cylinder fixed on a shaft whose ends project into the slideways above the ends of the plate cylinder shaft, said impression cylinder being adapted to run in rolling contact with the plate cylinder; e. upper bearing blocks slidably supported in the slideways and rotatably supporting the ends of the impression cylinder shaft; f. means for moving one of the cylinders with respect to the other cylinder to apply and relieve pressure at the line of contact between said plate and impression cylinders; g. means connecting the plate cylinder and the impression cylinder for synchronous rotation including:
 1. first helical gear means fixed on the shaft of the plate cylinder;
 2. second helical gear means engaging said first helical gear means;
 3. third helical gear means engaging said second helical gear means; and
 4. fourth helical gear means fixed on the shaft of the impression cylinder and engaging said third helical gear means; h. one of said second and third helical gear means comprising two gears rotatable about a common axis and splined together for concurrent rotation and relative axial movement, and means holding one of said two gears against axial movement; i. cam means for moving the othEr of said two gears axially in response to vertical movement of said one cylinder to introduce a compensating rotation into the gear train, so that the impression cylinder and the plate cylinder do not change their relative angular positions during that vertical movement.
 2. An intaglio printing press as in claim 1, in which: a. said cam means comprises a cam connected to the bearing block for said one cylinder for concurrent movement therewith; b. a follower for the cam connected to said other gear for concurrent rotation therewith; and c. spring means biasing said follower and said cam into engagement.
 2. means for selecting one or both of said wedge member driving means for operation; and
 2. a second wedge member, horizontally movable and having an inclined planar upper surface engaging said under surface of the first wedge member, and a horizontal under surface supported by said lower bearing block;
 2. second helical gear means engaging said first helical gear means;
 2. antifriction bearing means between said flanges and the cap;
 2. a second wedge member, horizontally movable and having an inclined planar upper surface engaging said under surface of the first wedge member, and a horizontal under surface supported by said lower bearing block;
 2. a first clutch member rotatable on the lead screw;
 3. motor means operable to move the upper bearing block vertically to apply and relieve pressure between the cylinders at their line of contact;
 3. an externally threaded shaft, fixed against rotation, said shaft being received in said nut and extending downwardly below the lower end of the nut;
 3. third helical gear means engaging said second helical gear means; and
 3. a pinion fixed to the first clutch member;
 3. motor means operable to move the upper bearing block vertically to apply and relieve pressure between the cylinders at their line of contact;
 3. means responsive to actuation of both said selecting means to actuate the selected clutch drive means; and
 3. An intaglio printing press as in claim 1, in which: a. said cam means comprises two spaced oppositely facing rotatable cams connected to the bearing block for said one cylinder for concurrent movement therewith; and b. two followers, one cooperating with each of said cams, and both fixed to said other gear, so that said other gear is positively driven in each direction by said cam means.
 4. An intaglio printing press as in claim 1, in which: a. the plate cylinder has a first portion of its peripheral surface adapted to support a printing plate, and a second portion of smaller radius than the first portion; b. motor means for driving said cylinder moving means; c. manual control means for said motor means; and d. interlocking means responsive to the angular position of the plate cylinder and effective to prevent actuation of said motor means except when the line of contact between the plate cylinder and the pressure cylinder is located at said second portion of the plate cylinder surface.
 4. means effective only after pressure is relieved to energize the sElected linear motor to change the axial spacing between the cylinders by a predetermined increment.
 4. a rack driven by the linear motor and cooperating with the pinion;
 4. fourth helical gear means fixed on the shaft of the impression cylinder and engaging said third helical gear means; h. one of said second and third helical gear means comprising two gears rotatable about a common axis and splined together for concurrent rotation and relative axial movement, and means holding one of said two gears against axial movement; i. cam means for moving the othEr of said two gears axially in response to vertical movement of said one cylinder to introduce a compensating rotation into the gear train, so that the impression cylinder and the plate cylinder do not change their relative angular positions during that vertical movement.
 4. means for driving the second wedge member horizontally to change the spacing between the cylinder axes;
 4. means for measuring the pressure between said plate and impression cylinders, including a load cell having an upper end supporting the lower end of the threaded shaft;
 4. means for driving the second wedge member horizontally to change the spacing between the cylinder axes;
 5. connecting means supporting the lower end of the load cell and fastened to the top of the bearing block;
 5. An intaglio printing press, comprising: a. frame means including opposed side frame members having opposed vertically extending slideways open at the top; b. a plate cylinder fixed on a shaft whose ends project into said slideways adjacent the lower ends thereof; c. lower bearing blocks slidably received in said slideways and rotatably receiving the ends of the shaft; d. an impression cylinder fixed on a shaft whose ends project into the slideways above the ends of the plate cylinder shaft, said impression cylinder being adapted to run in rolling contact with the plate cylinder; e. upper bearing blocks slidably supported in the slideways and rotatably supporting the ends of the impression cylinder shaft; f. a pair of caps fixed on said side frame members and closing the upper ends of the slideways; g. means on each cap for vertically moving the associated upper bearing block to apply and relieve pressure between said plate and impression cylinders, each said vertically moving means comprising:
 5. said means for driving the second wedge member includes a lead screw supported in said frame means and extending transversely of the slideway and threadedly engaging said second wedge member;
 5. second and third clutch members fixed to the lead screw and engageable selectively by said first clutch member for rotating the lead screw in one or the other direction in response to rotation of the first clutch member;
 5. piston means received in recess means in the upper surface of the first wedge member; and
 6. spring means biasing said piston means toward a position where its upper surface is above the upper surface of the first wedge member.
 6. clutch drive means operable selectively to shift the first clutch member into engagement with either of the second and third clutch members to select the direction of rotation of the lead screw; and
 6. spring means biasing said second wedge member in one direction along the lead screw, to take up lost motion between the second wedge member and the lead screw;
 6. An intaglio printing press as in claim 5, including compression spring means retained between the plate and the cap, said compression spring means comprising: a. a plurality of horizontally spaced cylinders having shouLders at their lower ends resting on the plate, and having projections on their lower ends received in recesses in the plate; b. a plurality of pistons, one slidable within each of said cylinders; and c. a spring compressed between each cylinder and its associated piston and biasing the piston upwardly into a recess in the cap; d. said cylinders having a dimension between their upper ends and said shoulders smaller than the spacing between said plate and said cap when the upper bearing block is in its pressure applying position, said cylinders serving to limit the travel of the upper bearing block in its pressure relieving direction.
 6. said nut having an internally splined projection extending above the upper end of the shaft and aligned with the axis of the shaft; and
 7. An intaglio printing press as in claim 5, including: a. an oil retaining housing mounted on the upper surface of the cap and enclosing the upper end of the nut and the lower end of the motor shaft; b. a second oil retaining housing mounted on the lower surface of the cap and enclosing the lower end of the nut and engaging the lower end of the shaft; c. said shaft having a skirt at its lower end encircling the upper end of the load cell; d. sealing means between the periphery of the skirt and the lower oil housing; and e. oil passages extending longitudinally through the nut and the shaft to relieve pressure developed in the housing upon rotation of the nut.
 7. a cage within said slideway for retaining said wedge members and holding them against lateral movement;
 7. control means for said clutch drive means.
 7. motor means mounted on the cap above the upper end of the nut for rotating the nut, said motor means having a downwardly extending shaft with external splines cooperating with the internal splines on the nut.
 8. An intaglio printing press as in claim 6, including: a. a first portion of the peripheral surface of said plate cylinder adapted to support a printing plate, and a second portion of smaller radius than the first portion; b. manual control means for said motor means; c. interlocking means responsive to the angular position of the plate cylinder and effective to prevent actuation of said motor means except when the line of contact between the plate cylinder and the pressure cylinder is located at said second portion of the plate cylinder surface; and d. means responsive to said load cell and operative to actuate said motor means in its pressure relieving sense at any angular position of the plate cylinder, whenever said pressure exceeds a predetermined value.
 8. means in one wall of the cage providing a journal for said lead screw; and
 9. stop means in a wall of the cage for limiting endwise movement of the second wedge member to a range of positions near the center position of said wedge member.
 9. An intaglio printing press as in claim 8, including lost motion means fastening the skirt to the connecting means, said lost motion means permitting downward movement of the skirt with respect to the plate as the load cell is compressed, but limiting the upward movement of the skirt away from the plate.
 10. An intaglio printing press as in claim 8, including means on the upper oil housing supporting said motor means, said upper oil housing having an aperture to accommodate the shaft of the motor means.
 11. An intaglio printing press, including: a. frame means including opposed side frame members having opposed vertically extending slideways open at the top; b. a plate cylinder fixed on a shaft whose ends project into said slideways adjacent the lower ends thereof; c. lower bearing blocks slidably received in said slideways and rotatably receiving the ends of the shaft; d. an impression cylinder fixed on a shaft whose ends project into the slideways above the ends of the plate cylinder shaft; e. upper bearing blocks slidably supported in the slideways and rotatably supporting the ends of the impression cylinder shaft; f. means for adjusting the axial spacing between the plate and impression cylinders, comprising, for each slideway:
 12. An intaglio printing press, including: a. frame means including opposed side frame members having opposed vertically extending slideways open at the top; b. a plate cylinder fixed on a shaft whose ends project into said slideways adjacent the lower ends thereof; c. lower bearing blocks slidably received in said slideways and rotatably receiving the ends of the shaft; d. an impression cylinder fixed on a shaft whose ends project into the slideways above the ends of the plate cylinder shaft; e. upper bearing blocks slidably supported in the slideways and rotatably supporting the ends of the impression cylinder shaft; f. means for adjusting the axial spacing between the plate and impression cylinders, comprising, for each slideway:
 13. An intaglio printing press as in claim 12, in which: a. said means for driving the second wedge member comprises:
 14. An intaglio printing press as in claim 13, including: a. manually operable control means for the motor means and the wedge member driving means, comprising: 